In-situ discrimination of the water cluster size distribution in aqueous solution by ToF-SIMS

The size distribution and molecular structure of water clusters play a critical role in the chemical,biological and atmospheric process.The common experimental study of water clusters in aqueous solution is challenged due to the influence of local H-bonding environments on vibration spectroscopies or vacuum requirements for most mass spectrometry technologies.Here,the time-of-flight secondary ion mass spectrometry(To F-SIMS)combining with a microfluidic chip has been applied to achieve the in-situ discrimination of the size distribution for water clusters in liquid water at room temperature.The results demonstrated that the presented method is highly system stable,reproducible and accurate.The comparison of heavy water with pure water was made to further demonstrate the accuracy of this technique.These results showed that(H_2O)_3H^+ and (D_2O)_4D^+ are the most dominant clusters in pure and heavy water,respectively.This one water molecule difference in the dominant cluster size may due to the nuclear quantum effects on water’s hydrogen bonded network.It is the first time to experimentally show the size distribution of water clusters over a wide range(n=1–30)for

Synthesis,characterization and catalytic performance of Mo based metal-organic frameworks in the epoxidation of propylene by cumene hydroperoxide

Two types of Mo containing metal-organic frameworks,denoted as Mo@COMOC-4 and PMA@MIL-101（Cr）,were synthesized respectively by a post-synthetic modification and a ship-in-bottle approach.The catalytic performance of both compounds in the epoxidation of propylene using cumene hydroperoxide（CHP） as oxidant was compared with MoO3@SiO2.A higher conversion（46.2%） and efficiency（87.4%） of CHP was observed for Mo@COMOC-4,whereas the heteropoly acids supported MIL-101 resulted in the decomposition of CHP due to its strong acidic character.Regenerability tests demonstrated that Mo@COMOC-4 could be reused for multiple runs without significant loss in both activity and stability.